1. Field of the Invention
The present invention relates to a tape-winding machine. More specifically, the present invention relates to a tensioning system for a concentric taping apparatus.
2. Description of the Related Art
Taping machines have been devised for applying tape about numerous products and product packages. Tape is applied to packages as they are advanced in a production line generally along the axis of the rotating machinery. The size and the nature of the tape will differ for different applications. Currently, some of the important factors and considerations in the design and the use of such taping machinery include the production output efficiency, the quality and consistency of the resulting product, the ease of replenishing tape that has been dispensed, and other factors that are well-known to those skilled in the art.
During use, the tape is applied in tension to the packages. One of the more significant problems that arise with taping machines is the ability to maintain a uniform tension in the tape as it is dispensed. Fluctuations in tape tension are affected both by the perfection in the tape pad and the package itself, as well as fluctuations and the rotational speeds of the various components, including the taping head.
Another attribute of conventional taping machines is that the tape tension tends to fluctuate between the time when the tape package is full and the tape is removed from a package having a greater diameter, to when the tape package is almost depleted when the tape is removed from such package having a smaller diameter. The constant change in the diameter of the package frequently contributes to differences in tension in the tape itself. Several types of braking mechanisms have been proposed in order to compensate or adjust the tension on the tape in an effort to maintain a substantially constant tension throughout the taping cycle.
The use of various mechanical brakes to control tension, such as disk brakes and band brakes, has important disadvantages. The use of friction-type mechanical braking components on machines that rotate at very high speeds has proven difficult to control and are inconsistent. Such attempts have not provided results that are entirely reliable, particularly at very high speeds. Since, in some instances, the tape pads can rotate as high as 1800 rpm, the centrifugal and centripetal forces have an adverse effect, even on electromagnetic units. However, even when using such mechanical or electromagnetic units, some sensing device must be used to sense the diameter of the tape packages at any given time so that the output of such sensor can be used in some way to compensate for the changes in tension.
Typically, optical sensors and ultrasonic sensors have been used to keep track of a tape roll's diameter. Here, again the results have been inconsistent and spikes have been observed in the tension of the tape because of the high speeds of rotation of mechanical parts, as well as because the use of optical sensors in dusty environments create operational difficulties. In electronic control systems, when tension spikes occur in the control signals they must be filtered out. Where conventional types of slip rings are used in a taping machine providing a control to compensate for tension spikes other inherent deficiencies result.
One tape applicator system has been proposed by Thermo Plastic Engineering Corporation (TEC”), which does not rely on mechanical brakes. In the TEC system the tape pad is driven directly by the main drive. The drive arm or guide system, or the tape head, is driven through a differential clutch, while the tape pad is driven directly by a main drive.
The output shaft of the clutch should preferably be connected to the low inertia components. However, in the TEC system, the output shaft of the clutch is connected to the high inertia guidance system or tape head. The output clutch is also coupled to an encoder, the output of which is connected to a control circuit that applies a control signal to the main drive. The output of the control circuit changes or adjusts the speed of the high inertia main drive and this tends to complicate the rest of the line as well as control over the main drive. Consequently, while the TEC system utilizes a differential clutch and avoids the use of mechanical braking components, the system introduces additional complications and shortcomings.